Experimental Design: Thirty-three patients with metastatic melanoma were treated in a cell dose–escalation trial of autologous TILs transduced with a gene encoding a single-chain IL12 driven by a nuclear factor of the activated T cells promoter (NFAT.IL12). No IL2 was administered.

Results: The administration of 0.001 to 0.1 × 109 NFAT.IL12–transduced TILs to 17 patients resulted in a single, objective response (5.9%). However, at doses between 0.3 and 3 × 109 cells, 10 of 16 patients (63%) exhibited objective clinical responses. The responses tended to be short, and the administered IL12-producing cells rarely persisted at 1 month. Increasing cell doses were associated with high serum levels of IL12 and IFNγ as well as clinical toxicities, including liver dysfunction, high fevers, and sporadic life-threatening hemodynamic instability.